Ptosis, or sagging of a female's breasts, is a natural consequence of gravity, weight gain and the aging process. It is most pronounced when the nipples extend below the point at which the underside of the breasts attach to the chest wall. Youthful, smaller breasts have a perceptively firm shape with a nipple that points outward. The most severe sagging breasts have nipples that point toward the ground.
The connective tissue that supports the breasts and provides structural integrity is known as Cooper's ligaments (also known as the suspensory ligaments of Cooper and the fibrocollagenous septa). Cooper's ligaments serve to divide the breast into compartments.
Because a woman's breasts grow in size during pregnancy, ligaments are stretched and gradually lose strength. The elastin in the skin also breaks down with smoking and other environmental effects and this alters reduces the firm appearance of the breasts.
Sagging is also affected by being overweight or repeated weight gains and losses. Generally, when the ligaments lengthen, the internal support of the breast weakens and the breast tissue sags under its own weight, losing its youthful firmness and contour.
Generally, sagging has been addressed by wearing a brassiere to physically prevent the appearance of the breasts from having a sagging appearance under clothing. Bra manufacturers typically advertise the ability to restore the shapely appearance of a woman's breasts at least while wearing their bra. However, compacting the breast with a bra may have adverse health consequences and studies have been published showing that wearing a bra may have an overall negative effect on sagging breasts.